A simple method for characterization of the magnetic field in an ion trap using Be+ ions

Abstract

We demonstrate a simple method for the determination of the magnetic field in an ion trap
using laser-cooled 9Be+ ions. The method is not based on magnetic resonance and
thus does not require delivering radiofrequency (RF) radiation to the trap. Instead,
stimulated Raman spectroscopy is used, and only an easily generated optical sideband of
the laser cooling wave is required. The d.c. magnetic vector, averaged over the
9Be+ ion ensemble, is determined. Furthermore, the field
strength can be minimized and an upper limit for the field gradient can be determined. The
resolution of the method is 0.04 G at present. The relevance for precision rovibrational
spectroscopy of molecular hydrogen ions is briefly discussed.